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Grade 11Mechanics

A simple pendulum of mass m and length l is oscillating along a circular arc of angle θ another bob of mass mis lying at the extreme position of the arc. The momentum ` imparted by the moving bob to the stationary bob will be(1) mlv/θ (2)mlv cosθ (3)MV sinθ (4)zero

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9 Years agoGrade 11
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ApprovedApproved Tutor Answer1 Year ago

To determine the momentum imparted by the moving bob of a simple pendulum to the stationary bob at the extreme position, we need to analyze the situation carefully. The key here is to understand how momentum is transferred during the interaction between the two bobs. Let's break this down step by step.

Understanding the Pendulum Motion

A simple pendulum consists of a mass (bob) attached to a string of length l, swinging back and forth under the influence of gravity. When the pendulum swings to an angle θ, it has potential energy at its highest point and kinetic energy at its lowest point. The momentum of the moving bob just before it reaches the extreme position is crucial for our analysis.

Calculating Momentum

The momentum (p) of an object is given by the formula:

  • p = mv

where m is the mass and v is the velocity of the bob. At the lowest point of its swing, the bob has maximum velocity. As it swings up to the extreme position, its velocity decreases due to the conversion of kinetic energy into potential energy.

Velocity at the Extreme Position

At the extreme position, the velocity of the moving bob can be derived from energy conservation principles. The kinetic energy at the lowest point is equal to the potential energy at the extreme position:

  • KE = PE
  • 1/2 mv² = mgh

Here, h is the height gained, which can be expressed in terms of the length of the pendulum and the angle θ:

  • h = l(1 - cosθ)

Substituting this into the energy equation allows us to find the velocity v just before the collision.

Collision Analysis

When the moving bob collides with the stationary bob at the extreme position, we consider the conservation of momentum. If we denote the velocity of the moving bob just before the collision as v and the stationary bob's initial momentum as zero, the total momentum before the collision is:

  • p_initial = mv

After the collision, if we assume an elastic collision (where both bobs move after the impact), the momentum will be shared between the two bobs. However, since the stationary bob starts from rest, the momentum imparted to it will be a fraction of the momentum of the moving bob.

Final Imparted Momentum

Given the options provided, we can analyze them based on our findings:

  • (1) mlv/θ - This does not represent the correct relationship.
  • (2) mlv cosθ - This could represent a component of momentum but is not the total imparted momentum.
  • (3) MV sinθ - This does not apply as we are not considering a different mass M.
  • (4) zero - This is incorrect as there is momentum transfer.

Thus, the correct answer is not explicitly listed among the options, but the momentum imparted is related to the velocity of the moving bob at the extreme position, which we derived from energy conservation principles. The momentum imparted will depend on the angle θ and the velocity of the moving bob at that point.

Conclusion

In summary, while the exact answer isn't among the options provided, the momentum imparted by the moving bob to the stationary bob is a function of its mass, velocity, and the angle of swing. Understanding the principles of momentum and energy conservation is crucial in analyzing such problems in physics.